Relay



Dec. 14, 1926. 1,610,552

' H. D. JAMES RELAY Filed Dec. 22. 1919 WITNESSES: INVENTOR flam yD. James W BY 4 Patented 14, 1926.

UNITED STATES PATENT OFFICE.

HENRY :0. JAMES, or nnenwoon PARK, rannsrnvanm, nssrenon ro wns'rme- HOUSE ELECTRIC a manuracrunme comrm, A com-cannon or rENNsYn VANIA.

' RELAY.

Application filed December 22, 1819. Serial No. 846,591.

My invention relates to electrical protective devices and particularly to thermal relays.

One object of my invention is to provide a thermal relay that shall have a sufficient" time interval in the operation thereof to effect protection of electrical apparatus against overloads.

Another object of my invention is -to provide a thermal relay, of the above indicated character, that shall not require the use of a separate heat-storage member.

A further object of my invention is to provide a helical spring that Shall have suflicient heat-storage capacity and torque to constitute aztlgermal relay of the above indicated characters- A further object of my invention is to provide a relay, of the-above indicated character, that shall be adapted to be used in ordinary standard cartridge-fuse clips, and be reliable and effective in its operation.

Heretofore, thermal relays having such characteristics that they conform to the heating characteristics of the device to be protected have been constructed without the use of a heating winding. These relays were for use in protecting devices of large current-carrying capacity where sufficient torque and heat-storagewapacity in a relay are easily obtained. Where thermal relays were employed in the protection of devices of low current capacity it was, however, difficult to obtain sufiicient torque and heatstorage capacity in a relay without the use of auxiliary heating means.

In View of the above, I provide a relay comprising a helical spring that isof such high resistance and of such mechanical strength that sufiicient heat-storage is obtained with the required operating torque. The spring is adapted'to expand to open a contact device when an overload obtains for a predetermined time on the device to be protected. In other words, the spring has a heating characteristic corresponding to the deviceto be protected, and no auxiliary heating coil or heat-storage member need be employed.

The single figure of the accompanying drawing'is a diagrammatic view of an electric circuit embodying my invention.

A motor 1 is connected to an electric circuit 2 and is provided with a circuit inter- .rupter 3 that is controlled by a thermal relay 4 for the purpose of disconnecting the motor 1 from the circuit 2, under predetermined conditions.

The relay 4 comprises a casing 5 constructed of insulating material and having connecting ferrules 6 and 7 at the ends thereof to be received by standard fuse clips, if desired. A pivot supporting member 8 is secured to the'ferrule 7 by a screw 9 which also constitutes a terminal 10 for the conductor 11 of the circuit 2. A member 12 is pivotally mounted. on the member 8 and comprises a laterally disposed arm 13 and a longitudinally disposed arm 14. A contact member 15 issecured to the arm 14 and is adapted to engage a stationary contact member 16 that is connected to one terminal of the holding coil 17 ofthe interrupter 3,

theother terminal of which is connected to the conductor 18 of the circuit 2. A helical spring 19 is connected at one end thereof to the ferrule 6 and at the other end thereof to the arm 13, thus occupying substantially the total length of the casing 5 and being of such resistance as to constitute a heatstorage member which, when sufiicient heat is stored therein, will expand to disengage the contact members 15 and 16 through the arms 13 and 14.

Since the resistance of the spring 19 is relatively large, the spring .may be of sufficient size, structurally, to obtain positive action in the operation of the member 12 and, thus, no external means need be employed to so heat the spring 19 as to cause the same to have a heating characteristic corresponding to the heating characteristic of the motorl. While it may be desirable to cause the member 19 to have a heating characteristic corresponding to the heating characteristic of the motor 1, for ordinary protective purposes, it is only necessary that. a suflicient time interval be obtained in the device to ensure that the circuit interrupter 3 will be opened by its spring 20 before the temperature of the motor 1 reaches a destructive value.

When sufficient current has traversed the 19 will expand to open the circuit through the'winding 17 and thus permit the spring 20 to open the interrupter 3. \Vhen the motor 1 and, consequently, the spring 19 have cooled to a predetermined degree, the contact members 15 will re-engage the contact member 16, and the circuit interrupter 3-- 1. A protective device for opening-an electric circuit containing electric apparatus upon a temperature rise above a predetermined value in said apparatus comprising a helical spring connected in circuit with said apparatus and having a heating characteristic corresponding to the heating characteristic of theapparatus andcircuit-interrupting means controlled thereby. 5

' 2. A thermal relay for electrical apparatus comprising an enclosing casing, connectca1 spring circuit with the apparatus and adapted toing ferrules at the ends thereof, and a heliwithin the casing connected in have such temperature characteristics that it. will expand a predetermined. amount only when the apparatus has been overloaded for a predetermined period of time. w I

3. A relay comprising a'cylindrical cartridge casing, a relatively long helical spring therein, a pivotally mounted member having arms of different lengths, one endof the spring'being connected toflthe shorter arm to actuate the same under predetermined thermal conditions,v and a contact member mounted on'the other arm of the member.

4. A thermal relay comprising a cylindrical casing, a movable contact member therein and a relatively long helical spring havng a large'heat-storage capacity for actuatmg the contact member.

5. .A thermal relay comprising an enclos-- ing cylindrical casing. a member pivotally mounted in one end of the 'caslng and having anarm extending longitudinally of the casing and an arm extending laterally of the casing, and a heat-responsive member disposed between the other end of the casing and the laterally extending arm to actuate the pivoted member when heated to a predetermined degree.

6. A thermal relay comprising an enclosing cylindrical casing, a member pivotally mounted in one end of the casing and having an arm extending longitudinally of the spring disposed between the other end of the i casing and the laterally. extending arm to actuate the pivoted member when heated to a predetermined degree.

8. A thermal relay comprising a cartridge casing, a pivotally mounted member therein having a laterally and a longitudinally extending arm, and a spring disposed in the casing for engaging the laterally extending arm to actuate the same when heated to a predetermined degree and having a relatively large heat-storage capacity.

9. A thermal relay comprising a cartridge casing, a pivotally mounted member in one end thereof having two arms, a contact member mounted on one arm, and anYexpansible spring disposed between the other end of the casing and the other arm to actuate the same when heated to a predetermined degree.

10. A relay for protecting an electrical translating device comprising a' casin a pivotally mounted member in one end ot the casing having two arms, a contact member mounted on one arm for controlling the circuit of the translating device, and a spring mounted between the other end of the casing and the other arm and being adapted to have the same time tem erature characteristic as the translating devlce to be protected and to actuate the pivotally-mounted member when heated to a predetermined degree.

11. A relay for protecting an electrical translating device comprising an enclosing casing, apivotally mounted member therein at one end of the casing having a laterally and a longitudinally extending arm, a contact member mounted on the longitudinally extending arm to, control the circuit of the translating device, and a helical spring dis posed between the other end of the casing and the laterally extending arm, said spring being adapted to actuate the laterally-extending arm when heated' to a predetermined degree and having suflicient heat-storage capacity to obtain a relatively long time element in the operation of the contact member. In testimony whereof, I have hereunto subscribed my name this 28th day of Novem ber 1919,

HENRY D. JAMES. 

